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Hoy-My Phung: Exploring the potential of semiconductor membrane lasers for a better thermal management and wavelength extension

Tampereen yliopisto
PaikkakuntaKorkeakoulunkatu 3, Tampere
Hervannan kampus, Sähkötalon auditorio SA203 ja etäyhteys
22.11.2021 10.00–14.00
PääsymaksuMaksuton tapahtuma
Hoy-My Phung.
Lasers have become ubiquitous in our daily life. With their wide applications in eye surgeries, telecommunications, sensing, and industrial cutting and welding processes, lasers have contributed to a better life quality and new products. As every application requires different laser specifications that vary in output power, beam quality, and wavelength, lasers are developed with many different types of light-amplifying media and architecture. During her doctoral research, Hoy-My Phung worked on semiconductor membrane lasers, which are abbreviated as MECSELs, a wavelength versatile laser platform with high power scaling potential.

Optically pumped semiconductor membrane lasers, known as MECSELs, have several striking advantages: They produce an excellent quality circular beam, which becomes important for applications, such as medical treatments, at which the laser beam needs to be focused down to a tiny spot. The light-amplifying medium is hereby realized as a semiconductor membrane, which is typically hundred times thinner than a human hair. For direct cooling, the membrane is sandwiched between two thermally conductive, high optical quality crystals. Exploring the limits of thermal management was one of the main research topics in Hoy-My Phung’s work.

“What extremely matters for the power performance in semiconductor lasers is the thermal management since semiconductors itself have a relatively low thermal conductivity. The semiconductor membrane laser is a good concept where the central element, a semiconductor membrane, is directly cooled from both sides. By this, we could use more affordable cooling crystals, which are manifolds cheaper than diamond, which represents the best choice in thermal conductivity, and at the same time available in wafer-scale. Also, all our lasers do not need to be cooled down to minus Celsius degrees and are able to operate at room temperature.”, explains Hoy-My Phung.

“For future power scaling, thicker membranes are already considered. In this case, it will get more challenging to insert energy across the membrane by striking the pump light from only one side of the whole semiconductor membrane. As such, not only the double-side cooling but also optical pumping from both, the front and the back side of the membrane will be beneficial.”, says Hoy-My Phung.

Alongside with the thermal investigations, Hoy-My Phung has demonstrated several MECSELs illuminating in the near-infra red in the 780 nm, 825 nm, and 1.5 µm telecom wavelength in the multi-Watt regime. Although these light sources are not aimed on any specific application in her work, they can be implemented in spectroscopic and light detection and ranging (LIDAR) applications.

Since 2018, Hoy-My Phung has been working on the development of semiconductor membrane lasers at the Optoelectronics Research Centre, Tampere University. The PhD research was embedded in the Academy of Finland project “Artificial laser Crystals (ALC)”.

The doctoral dissertation of M.Sc. Hoy-My Phung in the field of photonics titled Semiconductor Membrane External-Cavity Surface-Emitting Lasers (MECSELs): Power scaling, thermal management, and wavelength extension will be publicly examined in the Faculty of Engineering and Natural Sciences at Tampere University on Monday 22 November 2021 at 12:00 in the auditorium SA203 of the Sähkötalo Building, Korkeakoulunkatu 3, 33730 Tampere.  The Opponent will be Professor Arnaud Garnache from the University of Montpellier, France. The Custos will be Professor Mircea Guina from the Optoelectronics Research Centre, Faculty of Engineering and Natural Sciences, Tampere University.

The dissertation is available online at the http://urn.fi/URN:ISBN:978-952-03-2207-6.

The public can follow the event remotely.

Photo: Abhiroop Chellu